The way it matches images is incredibly unique. It doesn’t search on file name or size. I tried with thumbnails of my images, and it found the high res versions on sites I had submitted work to. It has a very cool way of reading a photo, and finding unique matches. I’ve been playing with it for a while now, and it doesn’t make mistakes.

TinEye is a reverse image search engine.
You give an image to TinEye to find out where it came from, how it is being
used, if modified versions of the image exist, or to find higher resolution
versions.